Do not use static type references when compiling for RustPython

[bschoenmaeckers]

Removed all usage of static type pointers when compiling for RustPython. Diff is large but is very repetitive.

Test plan

~/repo/pyo3 ❱ RUSTFLAGS="--cfg RustPython" cargo check
    Blocking waiting for file lock on build directory
    Checking pyo3-ffi v0.28.3 (/Users/basschoenmaeckers/repo/pyo3/pyo3-ffi)
    Checking pyo3 v0.28.3 (/Users/basschoenmaeckers/repo/pyo3)
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.38s

xref RustPython/RustPython#7562

https://discuss.python.org/t/c-api-add-py-getbuildintype-and-py-getbuildintypeborrowed/107010

[codspeed-hq]

Merging this PR will improve performance by 13.8%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 1 improved benchmark
✅ 104 untouched benchmarks
⏩ 1 skipped benchmark¹

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
⚡	bench_pyclass_create	4.6 µs	4 µs	+13.8%

---

_{Comparing bschoenmaeckers:RustPython-type-statics (e8b2d31) with main (8a00673)}

Footnotes

1. 1 benchmark was skipped, so the baseline result was used instead. If it was deleted from the codebase, click here and archive it to remove it from the performance reports. ↩

[davidhewitt]

There are a number of places in this PR where the extern blocks can be merged with one immediately above / below.

(I wonder if we could / should write a lint for that, maybe as part of the recently added machinery in the noxfile for formatting these?)

[bschoenmaeckers]

I've merged most adjacent blocks where the cfg attributes where the same. Please let me know I you see an other spot that needs cleaning.